Soils are susceptible to compaction for many reasons. It may be due to a poor particle size distribution (i.e. poor structure), a high clay content, a lack of organic matter, or other natural phenomena. It may be due to mechanical compaction such as that from athletes or livestock or heavy equipment.
Compacted soils tend to have poor drainage and become very hard when dry. In an arena without grass, this leads to impact and stress injuries and poor footing. In turf areas, in addition to the above, root growth may be inhibited, leading to stressed grasses, loss of vigor, and poor appearance. In both cases, a hard surface is substantially less safe than a resilient surface.
Previous attempts to address this problem have included incorporating a variety of soil amendments to alter the particle size distribution and the cohesiveness of the soil. These amendments include organic matter such as peat moss, saw dust, and straw, and synthetic materials such as rubber crumb derived from used tires and chopped athletic shoes.
Natural materials such as garden lime (actually powdered limestone) and gypsum (calcium sulfate) have also been used, but are largely ineffective in most cases, simply adding to the burden of too many fine particles. Sand has been used and has a particle size significantly larger than clay. However, unless a very large amount of sand is added, the clay tends to encapsulate the sand leading to minimal improvements in porosity.